For engines:
For gearboxes, my theory:
a) The gearbox identification number is not necessarily the same as engine number.
b) Gearbox numbers are probably in the same format as engine numbers (for example FE and FC Holdens have “L” prefix engines and gearboxes). There is likely to be some overlap between models (e.g. when the FB Holden was introduced, there may still have been some “L” gearbox cases leftover from the FC Holden run that were used).
c) The numbers above can be used to infer (very) approximate vehicle/gearbox number matches (for example an FB Holden gearbox probably has a number between B1001 and B183235). Note however that this is very approximate, and there is likely to be a lot of overlap – for example I have found a gearbox which should be from an FB Holden using the process above (B154496) which had EK Holden type first and reverse/second and third shifter lever cams.
For the gearboxes, casting dates are easy to read. Adjacent to the cast part number (on the main gearbox body aft of the bellhousing) is a casting clock and further cast number (see green arrow in the image above). The cast number consists of a letter followed by several (typically three, sometimes two with a space) digits. For example J259, D308, D218, F258, G288, M210, J6 1, G 249, E3 2, L257, G135, D 66, E287, K238, D218, A806, C 6 9 and M1 8. The cast number in the image to the right is G248.
The letters represent casting month, with the letter “I” not used i.e.:
• A = January
• B = February
• C = March
• D = April
• E = May
• F = June
• G = July
• H = August
• J = September
• K = October
• L = November
• M = December
The first two digits (or first digit and space) indicate casting day, whilst the last digit indicates the year (for example D308 being the 30th of April in a year ending in 8… it was on a FX/FJ casing, so probably 1948).
Cheers,
Harv